1. Field of the Invention
The present invention relates to a method for sealing electrical fittings, such as junction boxes, electrical conduit, and the like, using a foamable resin composition.
2. Description of the Prior Art
The current National Electrical Code requires conduit seals to prevent passage of gases, vapors, or flames from one portion of an electrical installation to another through the conduit when used in areas where flammable or explosive gases and vapors may be present, such as Class 1, Group D, Division 1 or 2 installations. Present conduit seals are made of shatterable material, such as a mixture of litharge and glycerine, bitumen, or a coal tar and resin composition, such as disclosed in U.S. Pat. No. 3,902,006, or foam materials such as silicone rubber, as disclosed in U.S. Pat. No. 4,401,491 or siloxane foam disclosed in U.S. Pat. No. 4,259,455. Rewiring of electrical fittings which are sealed with shatterable material can be difficult, time consuming, and expensive. To rewire such fittings, it usually is necessary to smash the fitting and chip away the sealant, cut the wires, cut the conduit each side of the smashed fitting to permit removal of the fitting, install a new conduit fitting and conduit couplings, reconnect the wires and seal the fitting. Electrical fitting seals of material such as siloxane foam and silicone rubber can also be difficult to remove. U.S. Pat. No. 3,985,951 discloses the use of actinic radiation activated expandable foam for use in electrical connectors. U.S. Pat. No. 4,388,681 discloses a light fixture having a foam-filled ballast compartment.